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Topic: Path to ground (Read 596 times) previous topic - next topic

Path to ground

How do our coaches get a path to earth ground when running on the genset?  I don't think this would be a hot skin issue as the power source is grounded to the coach. I was wondering about running power tools from the exterior outlet. ATS switch breaks the shore power but not the shore ground. Is this why it prudent to pull the shore plug when genset is on? Is the kitchen and exterior recpticles Daisy chained from bathroom gfic. Baffled somewhat as my shore power cord with the bad ground indicated by my outlet tester , when plugged into the coach my coach outlets test fine.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Path to ground

Reply #1 –
Phred, my understanding of ground is that it goes back to the winding on the generator. That is the ground. There is also a ground for the metal parts outside of it, so that won't carry a current. On a battery, it goes back to the negative post. That is also the ground. With AC power it goes to Earth ground.
 Don't have a ATS, so don't know the answer to that.  Neutral and grounds are one of those difficult to understand topics that don't seem to make a lot of sense. And they differ depending on the type of circuit they are on. I think the problem lies with the wording itself. Hope that helps.
Bob
'99 U320 40 WTFE
Build #5462,
1500 Watts Solar 600 amp Victron lithium
2012 Jeep Grand Cherokee Overland Hemi
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Retired
 

Re: Path to ground

Reply #2 –
Quote from: Old phart phred –
How do our coaches get a path to earth ground when running on the genset? 

They don't............ dont't need it....... The fault current path while running on the generator is back to the generator frame where the neutral conductor and the grounding conductor are bonded. Unless you drive a ground rod near the coach and bond it to the frame, it has no path back to the gen-set. "hot skin" will not be an issue UNLESS you have lost your grounding conductor back to the source (gen set).
As an example:
Your metal framed circular saw experiences a ground fault.....hot conductor to frame......and your round ground prong has been broken off, then you touch a metal portion of the coach (not the fiberglass skin of course) while holding that saw, you would experience a nasty shock. Hence the reason for the GFCI............. to protect you arse in this case.

If you are plugged in to pedestal power, the fault path is back to it's power source, the power company's transformer. At the first means of disconnect, usually near the meter, the "grounding" conductor is bonded to the "grounded" conductor and to a ground rod for "earth ground". In this case the correct fault path would be back through the saw power cord grounding conductor to the coach outlet, electrical panel, coach power cord and back to the pedestal. IF that path is broken the it would try to go through YOU to earth ground. The GFCI in the coach would still try to protect you as it measures any difference in current between the hot and the neutral conductor on it's circuit and any other path is considered fault current. Most are set to trip at a 5 milliamp difference, with 50 milliamps being considered as potentially fatal.

Hope I haven't confused the issue even more.
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota